Carbon-dots-conjugated semiconductors for enhanced solar-driven photocatalysis

In the last decades, the rising levels of carbon dioxide (CO2) in the atmosphere have been increasingly attributed to the global warming effect. Photocatalysis, which exploits the energy of light and abundant semiconductor materials, may represent a promising method to enable more sustainable catalytic reactions. However, the current applicability is mainly hindered by the design of materials capable of efficiently harvesting solar light to conduct photo-catalytic reactions. In this context, the conjugation of carbon dots with semiconductor materials was studied as tool to increase the visible-light sensitivity of titanium oxide (TiO2) and barium titanate (BaTiO3). The hybrid materials were tested for their photo-activity in two distinct reactions and upon the irradiation of either UV or solar light. Two different deposition methods were studied as to provide a scalable strategy to the design of versatile photocatalyst. As results, although all the prepared materials were found to be active in both UV and visible-light irradiating conditions, only carbon-modified semiconductors were able to convert CO2 into methane upon solar light excitation. In addition, carbon-dots-BaTiO3 conjugates were proposed for the first time as valid alternative to TiO2-based photocatalysts, especially in the CO2 photo-reduction reactions. If properly designed, carbon dots may represent a way to overcome some of the current limitations to the application of photocatalytic processes for the development solar-powered technologies.